The present invention relates to an aromatic condensed-ring compound, a material used for light emitting devices capable of luminescing through conversion of electric energy into light, and a light emitting device using such a material. In particular, the invention is concerned with a light emitting device suitably used in the areas of indicators, displays, backlight, electrophotography, illumination sources, recording light sources, exposure illuminants, reading light sources, beacons, signboards and interiors.
Nowadays, lively researches and developments in various display devices are being made. Of such devices, the organic electric-field luminescent (EL) devices are receiving particular attention as promising display devices because they can emit light of high intensity under low voltage. For instance, the Light emitting devices having organic thin films formed by vapor deposition of organic compounds are known (Applied Physics Letters, 51, p.913 (1987)). The organic Light emitting devices described in the literature cited above employ tris (8-hydroxyquinolinato)aluminum complex (Alq) as an electron transporting material and is structured to superimpose a layer of positive hole transporting material (an amine compound) on the layer of electron transporting material, and thereby show substantial improvements in their luminescent (light emitting) characteristics over conventional single-layer devices.
In recent years, the application of organic EL devices to full-color display has been examined actively. In order to develop high-performance full-color display, it is necessary to improve on the characteristics of conventional blue, green and red light emitting devices respectively. As to the blue light emitting devices, for instance, the distyrylarylene compounds (DPVBi) described in a book entitled xe2x80x9cOrganic EL devices and Forefront of Industrialization thereofxe2x80x9d, at page 38 (published by NTS Co.) have been studied extensively, but they have problems with color purity, durability, luminous intensity and efficiency, and so further improvements in these characteristics have been expected.
Although the organic light emitting devices comprising organic materials laminated by vacuum evaporation have really succeeded in luminescence (light emitting) of high luminance, the use of coating methods for manufacturing devices have advantages over that of vacuum evaporation methods from the viewpoints of simplicity of the manufacturing process, workability and ease in achievement of large-area luminescence. However, the devices, especially blue light emitting devices, manufactured according to conventional coating methods are inferior to those manufactured using vapor deposition methods in luminous intensity and luminous efficiency. Therefore, the development of novel blue luminescent materials has been awaited.
An object of the invention is to provide a light emitting device having satisfactory luminescence (light emitting) characteristics and durability, and a material enabling a light emitting device to have such characteristics.
The object is attained with the following means.
1. A light emitting device material comprising a compound represented by the following formula (1): 
wherein Ar11, Ar21 and Ar31 each represent an arylene group, Ar12, Ar22 and Ar32 each represent a substituent group or a hydrogen atom, provided that at least one of Ar11, Ar21, Ar31, Ar12, Ar22 and Ar32 has a phenanthrene structure or a condensed-ring aryl structure having at least four rings, and Ar represents a trivalent arene or heteroarene group.
2. A light emitting device material comprising a compound represented by the following formula (2): 
wherein Ar11, Ar21 and Ar31 each represents an arylene group, Ar12, Ar22 and Ar32 each represents a substituent group or a hydrogen atom, provided that at least one of Ar11, Ar21, Ar31, Ar12, Ar22 and Ar32 has a phenanthrene structure or a condensed-ring aryl structure having at least four rings, and R1, R2 and R3 each represents a hydrogen or a substituent.
3. A light emitting device material as described in item 1 or 2, wherein at least one of Ar11, Ar21, Ar31, Ar12, Ar22 and Ar32 has a condensed-ring aryl structure having at least four rings.
4. A light emitting device material as described in item 1, 2 or 3, wherein Ar11, Ar21 and Ar31 each represents a phenanthrenylene group or a condensed-ring arylene group having at least four rings.
5. A light emitting device material comprising a compound represented by formula (1a): 
wherein Ar11, Ar21 and Ar31 each represents an arylene group, Ar12a, Ar22a and Ar32a each represents a condensed-ring aryl group, and Ar represents a trivalent arene or heteroarene group.
6. A light emitting device material as described in item 5, wherein Ar12aAr22a and Ar32a each represents a condensed-ring aryl group having at least three rings.
7. A light emitting device material comprising a compound represented by formula (2a): 
wherein Ar11, Ar21 and Ar31 each represents an arylene group, Ar12a, Ar22a and Ar32a each represents a condensed-ring aryl group, and R1, R2 and R3 each represents a hydrogen or a substituent.
8. A light emitting device material as described in item 1, 2, 3 or 4, wherein Ar12, Ar22 and Ar32 each represents a phenathrene group or a condensed ring aryl group having at least four rings.
9. A light emitting device material as described in item 1, 2, 3, 4, 5, 6, 7 or 8, wherein the compound represented by formula (1) consists of carbon atoms and hydrogen atoms.
10. A compound represented by the following formula (3): 
wherein R11, R12 and R13 each represents a substituent group, R14, R15 and R16 each represents a hydrogen atom or a substituent, and q11, q12 and q13 each represents an integer of 0 to 9.
11. A light emitting device material comprising a compound of formula (3) defined in claim 10.
12. A compound represented by the following formula (4): 
wherein R41, R42 and R43 each represents a substituent group, R44, R45 and R46 each represents a hydrogen atoms or a substituent group, and q41, q42 and q43 each represents an integer of 0 to 9.
13. A light emitting device material comprising a compound of formula (4) defined in item 12.
14. A compound represented by the following formula (5): 
wherein R51 represents a substituent, R54, R55 and R56 each represents a hydrogen atoms or a substituent group, Ar51 represents an anthryl group, a phenanthryl group or a pyrenyl group, Ar52 represents a phenanthryl group or a pyrenyl group, and q51 each represents an integer of 0 to 9.
15. A light emitting device material comprising a compound of formula (5) defined in item 14.
16. A compound represented by the following formula (6): 
wherein R61 and R62 represents a substituent, and Ar61, Ar62, Ar63 and Ar64 each represents a condensed-ring aryl group.
17. A compound represented by the following formula (7): 
wherein R71, R72, R73 and R74 represents a substituent, R75 and R76 each represents a hydrogen atom or a substituent, and q71, q72, q73 and q74 each represents an integer of 0 to 9.
18. A light emitting device material comprising a compound of formula (7) defined in item 17.
19. A compound represented by the following formula (8): 
wherein R81, R82, R83 and R84 represents a substituent, R85 and R86 each represents a hydrogen atom or a substituent, and q81, q82, q83 and q84 each represents an integer of 0 to 9.
20. A light emitting device material comprising a compound of formula (8) defined in item 19.
21. A light emitting device comprising a pair of electrodes and one of a luminescent layer and a plurality of thin organic compound layers including a luminescent layer, wherein at least one layer is a layer comprising at least one light emitting device material as described in item 1, 2, 3, 4, 5, 6, 7, 8, 11, 13, 15, 18 or 20.
22. An organic light emitting device as described in item 21, wherein the layer comprising a light emitting device material as described in item 1, 2, 3, 4, 5, 6, 7, 8, 11, 13, 15, 18 or 20 is a layer formed in a coating process.
The invention is described below in detail. 
The formula (1) representing compounds according to the invention are illustrated first.
Ar11, Ar21 and Ar31 each represent an arylene group. The suitable number of carbon atoms contained in the arylene group is from 6 to 30, preferably from 6 to 20, and particularly preferably from 6 to 16. Examples of such an arylene group include a phenylene group, a naphthylene group, an anthrylene group, a phenanthrenylene group, a pyrenylene group, a perylenylene group, a fluorenylene group, a biphenylene group, a terphenylene group, a rubrenylene group, a chrysenylene group, a triphenylene group, a benzanthrylene group, a benzophenanthrenylene group and a diphenylanthrylene group. These arylene groups each may have a substituent group.
Examples of a substituent group on an arylene group include alkyl groups (containing preferably 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, particularly preferably 1 to 10 carbon atoms, such as methyl, ethyl, iso-propyl, tert-butyl, n-octyl, n-decyl, n-hexadecyl, cyclopropyl, cyclopentyl and cyclohexyl groups), alkenyl groups (containing preferably 2 to 30 carbon atoms, more preferably 2 to 20 carbon atoms, particularly preferably 2 to 10 carbon atoms, such as vinyl, allyl, 2-butenyl and 3-pentenyl groups), alkynyl groups (containing preferably 2 to 30 carbon atoms, more preferably 2 to 20 carbon atoms, particularly preferably 2 to 10 carbon atoms, such as propargyl and 3-pentynyl groups), aryl groups (containing preferably 6 to 30 carbon atoms, more preferably 6 to 20 carbon atoms, particularly preferably 6 to 12 carbon atoms, such as phenyl, p-methylphenyl, naphthyl and anthranyl groups), amino groups (containing preferably 0 to 30 carbon atoms, more preferably 0 to 20 carbon atoms, particularly preferably 0 to 10 carbon atoms, such as amino, methylamino, dimethylamino, diethylamino, dibenzylamino, diphenylamino and ditolylamino groups), alkoxy groups (containing preferably 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, particularly preferably 1 to 10 carbon atoms, such as methoxy, ethoxy, butoxy and 2-ethylhexyloxy groups), aryloxy groups (containing preferably 6 to 30 carbon atoms, more preferably 6 to 20 carbon atoms, particularly preferably 6 to 12 carbon atoms, such as phenyloxy, 1-naphthyloxy and 2-naphthyloxy groups), heteroaryloxy groups (containing preferably 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as pyridyloxy, pyrazyloxy, pyrimidyloxy and quinolyloxy groups), acyl groups (containing preferably 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as acetyl, benzoyl, formyl and pivaroyl groups), alkoxycarbonyl groups (containing preferably 2 to 30 carbon atoms, more preferably 2 to 20 carbon atoms, particularly preferably 2 to 12 carbon atoms, such as methoxycarbonyl and ethoxycarbonyl groups), aryloxycarbonyl groups (containing preferably 7 to 30 carbon atoms, more preferably 7 to 20 carbon atoms, particularly preferably 7 to 12 carbon atoms, such as phenyloxycarbonyl group), acyloxy groups (containing preferably 2 to 30 carbon atoms, more preferably 2 to 20 carbon atoms, particularly preferably 2 to 10 carbon atoms, such as acetoxy and benzoyloxy groups), acylamino groups (containing preferably 2 to 30 carbon atoms, more preferably 2 to 20 carbon atoms, particularly preferably 2 to 10 carbon atoms, such as acetylamino and benzxoylamino groups), alkoxycarbonylamino groups (containing preferably 2 to 30 carbon atoms, more preferably 2 to 20 carbon atoms, particularly preferably 2 to 12 carbon atoms, such as methoxycarbonylamino group), aryloxycarbonylamino groups (containing preferably 7 to 30 carbon atoms, more preferably 7 to 20 carbon atoms, particularly preferably 7 to 12 carbon atoms, such as phenyloxycarbonylamino group), sulfonylamino groups (containing preferably 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as methanesulfonylamino and benzenesulfonylamino groups), sulfamoyl groups (containing preferably 0 to 30 carbon atoms, more preferably 0 to 20 carbon atoms, particularly preferably 0 to 12 carbon atoms, such as sulfamoyl, methylsulfamoyl, dimethylsulfamoyl and phenylsulfamoyl groups), carbamoyl groups (containing preferably 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as carbamoyl, methylcarbamoyl, diethylcarbamoyl and phenylcarbamoyl groups), alkylthio groups (containing preferably 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as methylthio and ethylthio groups), arylthio groups (containing preferably 6 to 30 carbon atoms, more preferably 6 to 20 carbon atoms, particularly preferably 6 to 12 carbon atoms, such as phenylthio group), heteroarylthio groups (containing preferably 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as pyridylthio, 2-benzimidazolylthio, 2-benzoxazolylthio and 2-benzothiazolylthio groups), sulfonyl groups (containing preferably 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as mesyl and tosyl groups), sulfinyl groups (containing preferably 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as methanesulfinyl and benzenesulfinyl groups), ureido groups (containing preferably 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as ureido, methylureido and phenylureido groups), phosphoric acid amido groups (containing preferably 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as diethylphosphoric acid amido and phenylphosphoric acid amido groups), a hydroxyl group, a mercapto group, halogen atoms (such as fluorine, chlorine, bromine and iodine atoms), a cyano group, a sulfo group, a carboxyl group, a nitro group, a hydroxamic acid group, an imino group, heterocyclic groups (containing preferably 1 to 30 carbon atoms, more preferably 1 to 12 carbon atoms, and nitrogen, oxygen or/and sulfur atoms as hetero atoms, such as imidazolyl, pyridyl, quinolyl, furyl, thienyl, piperidyl, morpholino, benzoxazolyl, benzimidazolyl, benzothiazolyl, carbazolyl and azepinyl groups) and silyl groups (containing preferably 3 to 40 carbon atoms, more preferably 3 to 30 carbon atoms, particularly preferably 3 to 24 carbon atoms, such as trimethylsilyl and triphenylsilyl groups). The substituent groups as recited above may further be substituted.
Of the arylene groups as recited above, those preferred as each of Ar11, Ar21 and Ar31 are phenylene group, naphthylene group, anthrylene group, phenanthrenylene group, biphenylene group, and arylene group having at least four rings (e.g., pyrenylene, perylenylene). Of these groups, phenylene group, naphthylene group, phenanthrenylene group and arylene group having at least four rings are more preferred. Further, phenylene, phenanthrenylene and pyrenylene groups, especially pyrenylene group, are advantageous.
Ar12, Ar22 and Ar32 each represent a substituent group or a hydrogen atom. Examples of such a substituent group include the groups recited above as substituent groups with which Ar11 may be substituted. Preferably, Ar12, Ar22 and Ar32 are each a hydrogen atom, an aryl group, a heteroaryl group, an alkyl group or an alkenyl group. Of these groups, a hydrogen atom, an aryl group and a heteroaryl group are preferred over the others. Further, it is advantageous for each of Ar12, Ar22 and Ar32 to be a hydrogen atom or an aryl group, especially a hydrogen atom or a pyrenyl group.
However, at least one among Ar11, Ar21, Ar31, Ar12, Ar22 and Ar32 is required to have a phenanthrene structure or a condensed-ring aryl structure having at least four rings, preferably phenanthrene, pyrene and perylene structures, more preferably pyrene and phenanthrene structures, further preferably a pyrene structure.
Ar represents a trivalent arene group (containing preferably 6 to 30, more preferably 6 to 20, particularly preferably 6 to 16, carbon atoms, such as a trivalent benzene, naphthalene, anthracene, phenanthrene, pyrene or terphenyl group), or a trivalent heteroarene group (containing as a hetero atom preferably a nitrogen, sulfur or oxygen atom, more preferably a nitrogen atom, and further containing preferably 2 to 30, more preferably 3 to 20, particularly preferably 3 to 16, carbon atoms, such as a trivalent pyridine, pyrazine, thiophene, quinoline, quinoxaline or triazine group). Each of these groups may have a substituent group. Examples of such a substituent group include the groups recited above as substituent groups Ar11 may have. The group preferred as Ar is a trivalent group of benzene, naphthalene, anthracene, pyrene or terphenyl. In particular, it is advantageous for Ar to be a trivalent group of benzene, which preferably has no substituent groups, except Ar11, Ar21 and Ar31, or a trivalent group of alkyl-substituted benzene.
It is preferable for the compound of formula (1) to take a form represented by formula (2) or (6), more preferably formula (3), (4), (5), (7) or (8), further preferably formula (3). The present compound preferably consists of carbon atoms and hydrogen atoms. 
Formula (2) is explained below. Ar11, Ar21, Ar31, Ar12, Ar22 and Ar32 in formula (2) have the same meanings as Ar11, Ar21, Ar31, Ar12, Ar22 and Ar32 in formula (1) respectively. R1, R2 and R3 each represents a hydrogen or a substituent. Examples of such a substituent group include the groups recited hereinbefore as substituents which may be present on Ar11. R1, R2 and R3 each preferably represents a hydrogen, an aklyl group or an aryl group, more preferably a hydrogen or an alkyl group.
The compounds preferred as compounds represented by formula (1) or (2) are compounds in which at least one among Ar11, Ar21, Ar31, Ar12, Ar22 and Ar32 has a phenanthrene structure or a condensed-ring structure having at least four rings, more preferably a phenanthrene structure or pyrene structure. The compounds represented by formula (1) or (2) are preferably compounds wherein Ar12, Ar22 and Ar32 each represents a condensed-ring aryl group or a hydrogen atom, more preferably a condensed-ring aryl group having at least three rings or a hydrogen atom, further preferably a phenanthrene structure, a condensed-ring aryl structure having at least four rings or a hydrogen atom. The compounds represented by formula (1) or (2) are preferably compounds wherein Ar11, Ar21 and Ar31 each represents a phenanthrenylene group or a condensed-ring arylene having at least four rings.
Furthermore, it is advantageous for the compounds represented by formula (1) or (2) to be constituted of carbon and hydrogen atoms alone.
Formulas (1a) and (2a) are explained below. Ar, Ar11, Ar21, Ar31, R1, R2 and R3 in formulas (1a) and (2a) have the same meanings as those in formulas (1) and (2), respectively. Also, their preferred scopes are the same as those in formulas (1) and (2).
Examples of the condensed-ring aryl group represented by Ar12a, Ar22a and Ar32a include a naphthylene group, an anthrylene group, a phenanthrenylene group, a pyrenylene group, a perylenylene group, a fluorenylene group, a biphenylene group, a terphenylene group, a rubrenylene group, a chrysenylene group, a triphenylene group, a benzanthrylene group, a benzophenanthrenylene group and a diphenylanthracenylene group. These groups may further have a substituent group as explained in the substituent group for the arylene group of Ar11 to Ar31.
Formula (3) is explained below. In formula (3), R11, R12 and R13 each represent a substituent group. Examples of such a substituent group include the groups recited hereinbefore as substituents which may be present on Ar11. The groups preferred as R11, R12 and R13 include alkyl, alkenyl, aryl, heteroaryl and alkoxy groups. Of these groups, alkyl and aryl groups, especially aryl groups, are advantageous.
q11, q12 and q13 are each an integer of 0 to 9, preferably an integer of 0 to 3, more preferably an integer of 0 to 2, particularly preferably 0 or 1.
Formula (4) is explained below. R41, R42 and R43 each has the same meaning as R1 mentioned above, and their preferred scopes are the same as that of R1. q41, q42 and q43 are each an integer of 0 to 9, preferably an integer of 0 to 3, more preferably an integer of 0 to 2, particularly preferably 0 or 1.
Formula (5) is explained below. R51 has the same meaning as R11 mentioned above, and its preferred scope is the same as that of R11. R54, R55 and R56 each has the same meaning as R1 mentioned above, and its preferred scope is the same as that of R1. Ar51 represents an anthryl group, a phenanthryl group or a pyrenyl group. Ar51 represents a phenanthryl group or a pyrenyl group. Ar51 is preferably a phenanthryl group or a pyrenyl group. Ar52 is preferably a pyrenyl group. q51 represents an integer of 0 to 9, preferably an integer of 0 to 3, more preferably an integer of 0 to 2, particularly preferably 0 or 1.
Formula (6) is explained below. R61 and R62 each has the same meaning as R1 mentioned above, and its preferred scope is the same as that of R1. Ar61, Ar62, Ar63 and Ar64 each represents a condensed-ring aryl group, preferably a phenanthryl group or an aryl group having at least four rings, more preferably a phenanthryl group or a pyrenyl group.
Formula (7) is explained below. R71, R72, R73 and R74 each has the same meaning as R11 mentioned above, and its preferred scope is the same as that of R11. R75 and R76 each has the same meaning as R11 mentioned above, and its preferred scope is the same as that of R1. q71, q72, q73 and q74 are each an integer of 0 to 9, preferably an integer of 0 to 3, more preferably an integer of 0 to 2, particularly preferably 0 or 1.
Formula (8) is explained below. R81, R82, R83 and R84 each has the same meaning as R11 mentioned above, and its preferred scope is the same as that of R11. R85 and R86 each has the same meaning as R1 mentioned above, and its preferred scope is the same as that of R1. q81, q82, q83 and q84 are each an integer of 0 to 9, preferably an integer of 0 to 3, more preferably an integer of 0 to 2, particularly preferably 0 or 1.
The present compound may be a low molecular compound, or a oligomer or polymer compound (weight average molecular weight of which is preferably from 1,000 to 5,000,000, more preferably from 2,000 to 1,000,000, particularly preferably from 3,000 to 100,000, on a polystyrene basis). In the case of a polymer compound, the structure represented by formulas (1) to (8) may be present in the main chain or side chains of the polymer. And the polymer compound may be a homopolymer or copolymer compound. However, the present compound is preferably a low molecular compound.
Moreover, it is advantageous that the present compound shows the xcexmax of its fluorescent spectrum (maximum luminescent wavelength) in the region of 400 to 500 nm, preferably 400 to 480 nm, particularly preferably 400 to 460 nm.
Examples of the present compounds are illustrated below, but these examples should not be construed as limiting the scope of the invention in any way. 
In the second place, methods of synthesizing the present compounds are described below.
The present compounds can be synthesized utilizing reactions for forming bonds between aromatic carbons. For the bond formation can be adopted the methods described, e.g., in Organic Synthesis Reaction Guide, pp. 617-643, John Wiley and Sons, Inc., and Comprehensive Organic Transformation, pp. 5-103, VCH Co., Ltd. Of these known methods, the synthesis methods of forming carbon-carbon bonds in the presence of palladium catalysts are preferable. Further, it is advantageous to synthesize the intended compounds by reacting boric acid derivatives with aryl halide derivatives in the presence of palladium catalysts.
Examples of such boric acid derivatives include substituted or unsubstituted arylboric acid derivatives (such as 1,4-phenyldiboric acid, 4,4xe2x80x2-biphenyldiboric acid, pyreneboric acid derivative, phenanthreneboric acid derivative) and substituted or unsubstituted heteroarylboric acid derivatives (such as pyridyldiboric acid).
The halogen atoms of aryl halide derivatives are preferably chlorine, bromine or iodine atoms, particularly preferably bromine atoms.
The foregoing reactions have no particular restrictions as to palladium catalysts. Examples of palladium catalysts usable therein include palladium tetrakistriphenylphosphine, palladium carbon, palladium acetate and palladium dichloride (dppf) (dppf: 1,1xe2x80x2-bisdiphenylphosphinoferrocene). Ligands, such as triphenylphosphine, may be added simultaneously with those palladium catalysts.
In the reactions, it is preferable to use bases. The bases used are not particularly restricted in their kinds, but any of amines, such as sodium carbonate, sodium acetate and triethylamine, can be used. Also, the bases are not particularly restricted in their amounts used. However, the suitable amounts of bases used are from 0.1 to 20 equivalents, preferably from 1 to 10 equivalents, to the boric acid (ester) moiety.
In the reactions, it is also preferably to use solvents. Examples of solvents used, though they are not particularly restricted, include ethanol, water, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, dimethylformamide, toluene, tetrahydrofuran and mixtures of two or more thereof.
Then, light emitting devices comprising the present compounds are illustrated below.
It doesn""t matter what system, operation method or utilization mode is adopted by the present light emitting devices so long as the present compounds are used in the devices. However, the devices utilizing luminescence from the present compounds and the devices utilizing the present compounds as electron transport materials are preferred as the present devices. The representatives of light emitting devices are organic EL (electroluminescence) devices.
The organic layers of the devices containing the present compounds are not particularly restricted in their formation methods, but they can be formed using, e.g., a resistance heating vapor deposition method, an electron beam method, a sputtering method, a molecular lamination method, a coating method or an inkjet method. Of these methods, the resistance heating vapor deposition method and the coating method are preferred in the characteristic and manufacturing aspects.
Every light emitting device relating to the invention is a device in which a luminescent layer or at least two thin layers of organic compounds, including a luminescent layer, are formed between a pair of electrodes, namely an anode and a cathode. The thin layers the device may have in addition to the luminescent layer are, e.g., a hole injection layer, a hole transport layer, an electron injection layer, an electron transport layer and a protective layer. Each of these layers may have another function. For forming each layer, various materials can be employed.
The anode supplies holes to a hole injection layer, a hole transport layer and a luminescent layer. As anode materials, metals, alloys, metal oxides, electrically conductive materials and mixtures thereof, preferably materials having a work function of at least 4 eV, can be used. Examples of such materials include conductive metal oxides, such as tin oxide, zinc oxide, indium oxide and indium tin oxide (ITO), metals such as gold, silver, chromium and nickel, mixtures or laminates of those metals and conductive metal oxides, inorganic conductive materials such as copper iodide and copper sulfide, organic conductive materials such as polyaniline, polylthiophene and polypyrrole, and laminates of those materials and ITO. Of the materials recited above, the conductive metal oxides, especially ITO, are advantageous over the others from the viewpoints of productivity, conductivity and transparency. The suitable thickness of the anode, though can be selected depending on the anode material, is generally from 10 nm to 5 xcexcm, preferably 50 nm to 1 xcexcm, particularly preferably 100 nm to 500 nm.
In general the anode is used in the state of a layer formed on a soda lime glass, alkali-free glass or transparent resin substrate. In a case of using a glass substrate, alkali-free glass is preferred from the viewpoint of reduction in ions eluted from the glass. When soda glass is used as the substrate, it is desirable that the barrier coat, such as silica, be provided on the glass. The substrate thickness has no particular limitation so long as the substrate can ensure mechanical strength for the anode. For instance, the suitable thickness of a glass substrate is at least 0.2 mm, preferably at least 0.7 mm.
The methods suitable for making the anode vary with the material used. In the case of ITO, for example, the film formation can be carried out using an electron beam method, a sputtering method, a resistance heating vapor deposition method, a chemical reaction method (e.g., sol-gel method) or the method of coating a dispersion of indium tin oxide.
Washing and other treatments for the anode enable the device to get a reduction in operation potential and improve in light-emitting efficiency. In the case of an anode using ITO, it is effective for the anode to receive UV-ozone treatment or plasma treatment.
The cathode supplies electrons to an electron injection layer, an electron transport layer and a luminescent layer. In selecting the cathode, the adhesiveness to the electron injection, electron transport or luminescent layer adjacent to the cathode, the ionization potential and the stability are taken into consideration. As cathode materials, metals, alloys, metal halides, metal oxides, electrically conductive materials and mixtures thereof can be employed. Examples of such materials include alkali metals (e.g., Li, Na, K) and the fluorides thereof, alkaline earth metals (e.g., Mg, Ca) and the fluorides thereof, gold, silver, lead, aluminum, Naxe2x80x94K alloy or mixtures of two or more of these metals, Lixe2x80x94Al alloy or mixture, Mgxe2x80x94Ag alloy or mixture, and rare earth metals (e.g., In, Yb). Of these materials, the materials having a work function of at most 4 eV are advantageous over the others. In particular, aluminum, Lixe2x80x94Al alloy or mixture and Mgxe2x80x94Ag alloy or mixture are preferably used. The cathode may take a single-layer or made up of the compound or mixture as recited above or a lamination structure comprising the compounds or/and mixtures as recited above. The suitable thickness of the cathode, though can be chosen depending on the cathode material, is generally from 10 nm to 5 xcexcm, preferably 50 nm to 1 xcexcm, particularly preferably 100 nm to 1 xcexcm.
In forming the cathode, various known methods, such as an electron beam method, a sputtering method, a resistance heating vapor deposition method and a coating method, can be adopted. The metals as recited above may be evaporated independently, or two or more thereof may be evaporated simultaneously. Further, it is possible to evaporate a plurality of metals at the same time to form an alloy electrode, or to evaporate the previously prepared alloy.
It is advantageous to the light emitting device that both anode and cathode have low sheet resistance, specifically several hundreds xcexa9/xe2x96xa1 at the highest.
Any material can be used as a material for a luminescent layer so far as it can form a layer having a function of receiving both hole injection from the anode, the hole injection layer or the hole transport layer and electron injection from the cathode, the electron injection layer or the electron transport layer when the electric field is applied thereto, a function of permitting the charges injected therein to move and a function of enabling the emission of light by providing a place for recombining the holes and the electrons. Furthermore, the material for luminescent layer may emit a light from singlet exciton or triplet exciton.
Examples of such a material include benzoxazole derivatives, benzimidazole derivatives, benzothiazole derivatives, styrylbenzene derivatives, polyphenyl derivatives, diphenylbutadiene derivatives, tetraphenylbutadiene derivatives, naphthalimide derivatives, coumarin derivatives, perylene derivatives, perinone derivatives, oxadiazole derivatives, aldazine derivatives, pyraridine derivatives, cyclopentadiene derivatives, bisstyrylanthracene derivatives, quinacridone derivatives, pyrrolopyridine derivatives, thiadiazolo-pyridine derivatives, styrylamine derivatives, aromatic dimethylidyne derivatives, various metal complexes represented by metal or rare earth complexes of 8-quinolinol derivatives, polymeric compounds such as polythiophene, polyphenylene and polyphenylenevinylene, organic silane derivatives, and the present compounds. Although the luminescent layer has no particular restrictions as to the thickness, the suitable thickness thereof is generally from 1 nm to 5 xcexcm, preferably 5 nm to 1 xcexcm, particularly preferably 10 nm to 500 nm.
As to the method of forming the luminescent layer, there is no particular restrictions, but various methods including a resistance heating vapor deposition method, an electron beam method, a sputtering method, a molecular lamination method, a coating method (e.g., a spin coating, cast coating or dip coating method), an ink jet method and an LB method can be adopted. Of these methods, resistance heating vapor deposition and coating methods are favored over the others.
The materials for the hole injection layer and the hole transport layer may be any materials so long as they have any one of the functions as an injector of holes from the anode, a transporter of holes and a barrier against electrons injected from the cathode. Examples of materials hitherto known to have one of such functions include carbazole derivatives, triazole derivatives, oxazole derivatives, oxadiazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives, pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, amino-substituted chalcone derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, stilbene derivatives, silazane derivatives, aromatic tertiary amine compounds, styrylamine compounds, aromatic dimethylidyne compounds, porphyrin compounds, polysilane compounds, conductive polymers and oligomers such as poly(N-vinylcarbazole) derivatives, aniline copolymers, thiophene oligomers and polythiophene, organic silane compounds, carbon membranes, and the present compounds. The suitable thickness of the hole injection layer and the hole transport layer each, though it has no particular limitation, is generally from 1 nm to 5 xcexcm, preferably 5 nm to 1 xcexcm, particularly preferably 10 nm to 500 nm. Each of the hole injection layer and the hole transport layer may have a single-layer structure constituted of one or more of the materials recited above or a multiple-layer structure made up of at least two layers having the same composition or different compositions.
As a method of forming the hole injection or transport layer, a vacuum evaporation method, an LB method, a method of coating a hole-injecting or transporting material in the form of a solution or dispersion in an appropriate solvent (using, e.g., a spin coating, cast coating or dip coating method) and an ink jet method can be adopted. When the coating method is adopted, the agent to constitute the layer may be dissolved or dispersed in a coating solvent, together with a resinous ingredient. Examples of such a resinous ingredient include polyvinyl chloride, polycarbonate, polystyrene, polymethyl methacrylate, polybutylmethacrylate, polyester, polysulfone, polyphenylene oxide, polybutadiene, poly(N-vinylcarbazole), hydrocarbon resin, ketone resin, phenoxy resin, polyamide, ethyl cellulose, polyvinyl acetate, ABS resin, polyurethane, melamine resin, unsaturated polyester resin, alkyd resin, epoxy resin and silicone resin.
The materials for the electron injection layer and the electron transport layer may be any materials so long as they have any one of the functions as an injector of the electrons from the cathode, a transporter of electrons and a barrier against holes injected from the anode. Examples of compounds known to have such a function include triazole derivatives, oxazole derivatives, oxadiazole derivatives, fluorenone derivatives, anthraquinodimethane derivatives, anthrone derivatives, diphenylquinone derivatives, thiopyran dioxide derivatives, carbodimide derivatives, fluorenylidenemethane derivatives, distyrylpyrazine derivatives, tetracarboxylic acid anhydrides of aromatic rings such as naphthalene and perylene, phthalocyanine derivatives, various metal complexes represented by metal complexes of 8-quinolinol derivatives, metallophthalocyanines and metal complexes having benzoxazole or benzothiazole ligands, organic silane derivatives and the present compounds. The suitable thickness of the electron injection layer and the electron transport layer each, though it has no particular limitation, is generally from 1 nm to 5 xcexcm, preferably 5 nm to 1 xcexcm, particularly preferably 10 nm to 500 nm. Each of the electron injection layer and the electron transport layer may have a single-layer structure constituted of one or more of the materials as recited above, or a multiple-layer structure made up of at least two layers having the same composition or different compositions.
As a method of forming the electron injection layer and the electron transport layer, a vacuum evaporation method, an LB method, a method of coating the electron-injecting or transporting material as recited above in the form of a solution or dispersion in an appropriate solvent (using, e.g., a spin coating, cast coating or dip coating method) and an ink jet method can be adopted. In the case of adopting a coating method, the electron-injecting or transporting agent can be dissolved or dispersed together with a resinous ingredient. Examples of a resinous ingredient usable therein include the same resins as employed for the hole injection and transport layers.
The materials for a protective layer may be any substances so long as they have a function capable of inhibiting the invasion of a device deterioration promoter, such as moisture or oxygen, into the device. Examples of such a substance include metals such as In, Sn, Pb, Au, Cu, Ag, Al, Ti and Ni, metal oxides such as MgO, SiO, SiO2, Al2O3, GeO, NiO, CaO, BaO, Fe2O3, Y2O3 and TiO2, metal fluorides such as MgF2, LiF, AlF3 and CaF2, polyethylene, polypropylene, polymethyl methacrylate, polyimide, polyurea, polytetrafluoroethylene, polychlorotrifluoroethylene, polydichlorodifluoroethylene, copolymer of chlorotrifluoroethylene and dichlorodifluoro-ethylene, copolymers prepared by polymerizing a mixture of tetrafluoroethylene and at least one comonomer, and fluorine-containing copolymers having cyclic structures on the main chain, a water-absorbing substance having a water absorption rate of at least 1%, and a moistureproof substance having a water absorption rate of at most 0.1%.
The protective layer also has no particular restriction as to the formation method, but any of a vacuum evaporation method, a sputtering method, a reactive sputtering method, a molecular beam epitaxy (MBE) method, a cluster ion beam method, an ion plating method, a plasma polymerization method (high frequency excitation ion plating method), a plasma chemical vapor deposition (CVD) method, a laser CVD method, a heat CVD method, a gas source CVD method and a coating method can be adopted for the formation thereof.
The present invention will now be illustrated in more detail by reference to the following examples. However, the invention should not be construed as being limited to these examples.
To a mixture of 1.0 g of pyreneboric acid ester (a), 0.29 g of 1,3,5-tribromobenzene, 0.6 g of sodium carbonate, 0.05 g of triphenylphosphine and 0.05 g of palladium carbon, 20 ml of diethylene glycol dimethyl ether and 20 ml of water were added, followed by stirring under reflux. After 6 hours, the reaction solution was diluted with 200 ml of chloroform and 200 ml of water, and subjected to cerite filtration. The organic layer obtained was washed with 100 ml each of water for two times, dried over sodium sulfate, and then concentrated. The concentrate obtained was purified by column chromatography (chloroform), and further purified by re-crystallization (chloroform/methanol) to yield 0.5 g of Compound (1-1). A vacuum evaporation film of Compound (1-1) was formed, and the fluorescence thereof was measured. The fluorescence maximum wavelength (xcexmax) of this film was 480 nm. The glass transition (Tg) temperature of the compound was 164xc2x0 C. 
To a mixture of 1.5 g of phenanthreneboric acid ester, 0.47 g of 1,3,5-tribromobenzene, 1.6 g of sodium carbonate, 0.07 g of triphenylphosphine and 0.07 g of palladium carbon, 30 ml of diethylene glycol dimethyl ether and 30 ml of water were added, followed by stirring under reflux. After 6 hours, the reaction solution was diluted with 200 ml of chloroform and 200 ml of 1-N hydrochloric acid water, and subjected to cerite filtration. The organic layer obtained was washed with 100 ml each of water for two times, dried over sodium sulfate, and then concentrated. The concentrate obtained was purified by column chromatography (hexane/ethyl acetic acid system), and further purified by re-crystallization (chloroform/methanol) to yield 1.0 g of Compound (1-2). The structure of Compound (1-2) was confirmed with MS spectra. A vacuum evaporation film of Compound (1-2) was formed, and the fluorescence thereof was measured. The fluorescence maximum wavelength (xcexmax) of this film was 380 nm. 
To a mixture of 1.0 g of pyreneboric acid ester, 0.28 g of 1,2,4,5-tetrabromobenzene, 0.88 g of sodium carbonate, 0.05 g of triphenylphosphine and 0.05 g of palladium carbon, 30 ml of diethylene glycol dimethyl ether and 30 ml of water were added, followed by stirring under reflux. After 6 hours, the reaction solution was diluted with 200 ml of chloroform and 200 ml of 1-N hydrochloric acid water, and subjected to cerite filtration. The organic layer obtained was washed with 100 ml each of water for two times, dried over sodium sulfate, and then concentrated. The concentrate obtained was purified by column chromatography (chloroform), and further purified by re-crystallization (chloroform/methanol) to yield 0.4 g of Compound (1-39). The structure of Compound (1-39) was confirmed with MS spectra. 
To a mixture of 1.15 g of phenanthreneboric acid ester, 0.35 g of 1,2,4,5-tetrabromobenzene, 0.96 g of sodium carbonate, 0.07 g of triphenylphosphine and 0.07 g of palladium carbon, 30 ml of diethylene glycol dimethyl ether and 30 ml of water were added, followed by stirring under reflux. After 6 hours, the reaction solution was diluted with 200 ml of chloroform and 200 ml of 1-N hydrochloric acid water, and cooled to a room temperature and subjected to cerite filtration. The separated solid was dissolved in chloroform, and subjected to cerite filtration so as to remove palladium carbon. The, the solution was purified by column chromatography (chloroform), and further purified by re-crystallization (chloroform/methanol) to yield 0.5 g of Compound (1-40). The structure of Compound (1-40) was confirmed with MS spectra. A vacuum evaporation film of Compound (1-40) was formed, and the fluorescence thereof was measured. The fluorescence maximum wavelength (xcexmax) of this film was 440 nm. 
250 ml of diethyl ether was added to 25 g of 1,3,5-tribromobenzene, and the mixture was cooled to xe2x88x9278xc2x0 C. in a nitrogen stream. 52 ml of n-butyllithium (1.6M hexane solution) was dropped to the mixture, and then the temperature of the mixture was increased to a room temperature. 15.4 g of anthrone was separately added to the mixture, followed by stirring for three hours under flux while heating. To the solution cooled to a room temperature, 500 ml of ethyl acetate and 300 ml of 1-N hydrochloric acid water were added, and the organic layer was separated out. The organic layer was washed with 300 ml of saturated solution of salt, and then concentrated. The concentrate obtained was purified by column chromatography (chloroform) to obtain 1.5 g of Intermediate A (Compound A)
To a mixture of 0.84 g of pyreneboroic acid ester, 0.5 g of Compound A, 0.51 g of sodium carbonate, 0.05 g of triphenylphosphine and 0.05 g of palladium carbon, 30 ml of diethylene glycol dimethyl ether and 30 ml of water were added, followed by stirring under reflux. After 6 hours, the reaction solution was cooled to a room temperature and subjected to cerite filtration. The separated solid was dissolved in chloroform, and subjected to cerite filtration so as to remove palladium carbon. The, the solution was purified by column chromatography (chloroform), and further purified by re-crystallization (chloroform/methanol) to yield 0.3 g of Compound (1-35). The structure of Compound (1-35) was confirmed with MS spectra. 
150 ml of diethyl ether was added to 10 g of 1,3,5-tribromobenzene, and the mixture was cooled to xe2x88x9278xc2x0 C. in a nitrogen stream. 41.7 ml of n-butyllithium (1.6M hexane solution) was dropped to the mixture, and then the temperature of the mixture was increased to a room temperature. 13.0 g of anthrone was separately added to the mixture, followed by stirring for three hours under flux while heating. After removing dithyl ether by distillation, 200 ml of toluene and 0.1 g of paratoluene sulfonate were added to the solution, followed by stirring under reflux while heating. To the solution cooled to a room temperature, 300 ml of chloroform and 300 ml of water were added, and the organic layer was separated out and concentrated. The concentrate obtained was purified by column chromatography (chloroform), and crystallized (chloroform/hexane) to obtain 2.0 g of Intermediate B (Compound B).
To a mixture of 0.27 g of pyreneboroic acid ester, 0.4 g of Compound B, 0.17 g of sodium carbonate, 0.05 g of triphenylphosphine and 0.05 g of palladium carbon, 30 ml of diethylene glycol dimethyl ether and 30 ml of water were added, followed by stirring under reflux. After 6 hours, the reaction solution was cooled to a room temperature and subjected to cerite filtration. The separated solid was dissolved in chloroform, and subjected to cerite filtration so as to remove palladium carbon. The, the solution was purified by column chromatography (hexane/ethyl acetate system to chloroform system), and further purified by re-crystallization (chloroform/methanol) to yield 0.1 g of Compound (1-37). The structure of Compound (1-37) was confirmed with MS spectra. 